Class LayerUtility


  • public class LayerUtility
    extends java.lang.Object
    This class allows to import pages as Form XObjects into a document and use them to create layers (optional content groups). It should used only on loaded documents, not on generated documents because these can contain unfinished parts, e.g. font subsetting information.
    • Field Detail

      • LOG

        private static final org.apache.commons.logging.Log LOG
      • PAGE_TO_FORM_FILTER

        private static final java.util.Set<java.lang.String> PAGE_TO_FORM_FILTER
    • Constructor Detail

      • LayerUtility

        public LayerUtility​(PDDocument document)
        Creates a new instance.
        Parameters:
        document - the PDF document to modify
    • Method Detail

      • getDocument

        public PDDocument getDocument()
        Returns the PDF document we work on.
        Returns:
        the PDF document
      • wrapInSaveRestore

        public void wrapInSaveRestore​(PDPage page)
                               throws java.io.IOException
        Some applications may not wrap their page content in a save/restore (q/Q) pair which can lead to problems with coordinate system transformations when content is appended. This method lets you add a q/Q pair around the existing page's content.
        Parameters:
        page - the page
        Throws:
        java.io.IOException - if an I/O error occurs
      • importPageAsForm

        public PDFormXObject importPageAsForm​(PDDocument sourceDoc,
                                              int pageNumber)
                                       throws java.io.IOException
        Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.

        You may want to call wrapInSaveRestore(PDPage) before invoking the Form XObject to make sure that the graphics state is reset.

        Parameters:
        sourceDoc - the source PDF document that contains the page to be copied
        pageNumber - the page number of the page to be copied
        Returns:
        a Form XObject containing the original page's content
        Throws:
        java.io.IOException - if an I/O error occurs
      • importPageAsForm

        public PDFormXObject importPageAsForm​(PDDocument sourceDoc,
                                              PDPage page)
                                       throws java.io.IOException
        Imports a page from some PDF file as a Form XObject so it can be placed on another page in the target document.

        You may want to call wrapInSaveRestore(PDPage) before invoking the Form XObject to make sure that the graphics state is reset.

        Parameters:
        sourceDoc - the source PDF document that contains the page to be copied
        page - the page in the source PDF document to be copied
        Returns:
        a Form XObject containing the original page's content
        Throws:
        java.io.IOException - if an I/O error occurs
      • appendFormAsLayer

        public PDOptionalContentGroup appendFormAsLayer​(PDPage targetPage,
                                                        PDFormXObject form,
                                                        java.awt.geom.AffineTransform transform,
                                                        java.lang.String layerName)
                                                 throws java.io.IOException
        Places the given form over the existing content of the indicated page (like an overlay). The form is enveloped in a marked content section to indicate that it's part of an optional content group (OCG), here used as a layer. This optional group is returned and can be enabled and disabled through methods on PDOptionalContentProperties.

        You may want to call wrapInSaveRestore(PDPage) before calling this method to make sure that the graphics state is reset.

        Parameters:
        targetPage - the target page
        form - the form to place
        transform - the transformation matrix that controls the placement of your form. You'll need this if your page has a crop box different than the media box, or if these have negative coordinates, or if you want to scale or adjust your form.
        layerName - the name for the layer/OCG to produce
        Returns:
        the optional content group that was generated for the form usage
        Throws:
        java.io.IOException - if an I/O error occurs
      • transferDict

        private void transferDict​(COSDictionary orgDict,
                                  COSDictionary targetDict,
                                  java.util.Set<java.lang.String> filter,
                                  boolean inclusive)
                           throws java.io.IOException
        Throws:
        java.io.IOException
      • importOcProperties

        private void importOcProperties​(PDDocument srcDoc)
                                 throws java.io.IOException
        Imports OCProperties from source document to target document so hidden layers can still be hidden after import.
        Parameters:
        sourceDoc - The source PDF document that contains the /OCProperties to be copied.
        Throws:
        java.io.IOException - If an I/O error occurs.